Mechanism Analysis of Streamer Branching in Insulating Oil Discharge Processes

Streamer branching phenomena are commonly observed in gas and liquid discharge processes, displaying significant randomness. The stochastic nature that drives streamer branching is primarily attributed to background noise during the initial state, impurities in the medium, and non-uniform distribution caused by fluctuations in carrier density. In this study, we propose a two-dimensional streamer model that incorporates carrier density fluctuations and investigate differences in streamer propagation under various externally applied voltage conditions. The results indicate significant variations in the propagation velocity of the main streamer channel under lightning impulse and pulse voltage conditions, while the size and quantity of streamer branching are influenced by both the excitation type and voltage magnitude. Higher voltages lead to faster propagation of the main streamer channel in the direction of the electric field and an increased number of streamer branches. The rising edge of the applied voltage determines the initiation time of streamer coronas and influences both the overall diameter and discharge velocity of the streamer channels.